Various in vivo measurement systems are known in the art. They typically include swallowable electronic capsules which collect data and which transmit the data to a receiver system. These intestinal capsules, which are moved through the digestive system through the action of digestion, are often called "Heidelberg" capsules and are utilized to measure pH, temperature and pressure throughout the intestines. They have also been utilized to measure gastric residence time, which is the time it takes for food to pass through the stomach and intestines.
The intestinal capsules typically include a measuring system and a transmission system, where the transmission system transmits the measured data at radio frequencies to the receiver system.
The following articles describe swallowable electronic capsules:
E. N. Rowland and H. S. Wolff, "The Radio Pill: Telemetering from the Digestive Tract", British Communications and Electronics, August 1960, pp. 598-601; and
Yarborough, D. R. III, et al., "Evaluation of the Heidelberg Capsule: Method of Tubeless Gastric Analysis", The American Journal of Surgery, Vol. 117, February 1969, pp. 185-191.
Other in vivo measuring systems are endoscopes, long tubes which the patient swallows. These are often utilized to provide images of the upper or lower gastro-intestinal tract. However, because they are not very flexible, they do not move easily through small intestines, and thus, they do not provide views of the small intestines.
There are currently two types of endoscopes. Fiber-optic endoscopes utilize a fiber optic waveguide to transmit the video signal from the area of interest to the electronics located outside the patient's body. Video endoscopes place an electronic camera at the area of interest and store the images until after the test finishes.